Nonaqueous electrolyte battery including package member having blackbody material layer

ABSTRACT

A nonaqueous electrolyte battery is provided which includes a battery element, and a package member for packaging the battery element, and in the nonaqueous electrolyte battery, the package member includes a layer which contains a blackbody material capable of using blackbody radiation and which has an emissivity of 0.6 or more.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/910,527, filed Oct. 22, 2010, which application claimspriority to Japanese Priority Patent Application JP 2009-250418 filed inthe Japan Patent Office on Oct. 30, 2009, the entire content of which ishereby incorporated by reference.

BACKGROUND

The present invention relates to a nonaqueous electrolyte battery, andmore particularly relates to a nonaqueous electrolyte battery havinghigh heat dissipation characteristics.

In recent years, reduction in size and weight of mobile informationterminals, such as a mobile phone, a notebook type personal computer,and a personal digital assistant (PDA), has been rapidly advanced, andhence batteries used as a drive power source therefor are stronglydesired to have a higher capacity. Since having a high energy densityand a high capacity, nonaqueous electrolyte batteries represented by alithium ion secondary battery have been widely used as a drive powersource for the mobile information terminals mentioned above.

Technical development on the safety of a related lithium ion battery hasbeen carried out in consideration of the cases of various incorrectuses. In view of suppression of heat generation, the above technicaldevelopment can be further roughly categorized into two types, that is,an improvement in properties of battery materials and an improvement instructure and mechanism of batteries. The development of a flameretardant electrolyte, the use of positive and negative active materialswhich generate a small amount of heat, and the like are categorized intothe former group, and the prevention of overcharge and over-discharge byan external protective circuit, the reduction in inside pressure by asafety valve in gas ejection, and the like are categorized into thelatter group.

For example, as disclosed in Japanese Unexamined Patent ApplicationPublication No. 2002-208439, as for the structure to improve the heatconduction, a technique in which an anode or a cathode is thermallycontacted to a metal package has been proposed.

SUMMARY

However, in Japanese Unexamined Patent Application Publication No.2002-208439, as for the promotion of heat dissipation, the heatconduction inside a battery and the heat transfer between an outersurface of the battery and the outside environment are only taken intoconsideration; hence, a new and significant technique has not beendeveloped. Hence, the use of a battery material having a high safety hasbeen a fairly difficult subject due to a trade-off with the performance,such as the battery capacity, and a time period necessary for searchinga novel material. In addition, as for the suppression of heat generationby a novel battery structure and mechanism, a new and significanttechnique has also been desired.

In view of the promotion of heat dissipation which is another approachto the technical development in safety, it is believed that the use of abattery material having an excellent heat conductivity leads to thepromotion of heat dissipation (for example, see Japanese UnexaminedPatent Application Publication No. 62-119859). However, again, thebattery material was not easily changed due to the trade-off with theperformances.

As for the heat dissipation, besides the heat conduction and the heattransfer, each of which is caused by a heat flux proportional to thedifference in temperature, a phenomenon has been understood in whichheat radiation produces a heat flux proportional to the difference inthe fourth power of temperature; however, an attempt to use thisphenomenon has been rarely carried out. The reason for this is supposedthat since the radiation becomes dominant when the temperature isextremely high, such as several thousands degrees centigrade, comparedto room temperature, it is prejudiced that the radiation has no effecton internal heat generation of a battery at a temperature of at mostseveral hundreds degrees centigrade.

In consideration of the problem described above, it is desirable toprovide a nonaqueous electrolyte battery capable of improving its heatdissipation characteristics and of exhibiting a high safety even if heatis generated inside the battery.

According to an embodiment of the present invention, there is provided anonaqueous electrolyte battery which includes a battery element, and apackage member for packaging the battery element, and in this nonaqueouselectrolyte battery, the package member has a layer which contains ablackbody material capable of using blackbody radiation and which has anemissivity of 0.6 or more.

It is preferable that the package member includes an outer layer film, ametal foil, an inner layer film, and an adhesive layer, and at least oneof the outer layer film, the inner layer film, and the adhesive layercontains the blackbody material, or the package member includes ablackbody material layer containing the blackbody material between theouter layer film and the metal foil or between the metal foil and theinner layer film.

It is preferable that the blackbody material layer containing theblackbody material is provided between the metal foil and the outerlayer film or that the outer layer film contains the blackbody material.

It is preferable that the blackbody material includes at least one of acarbon material, a silicate material, and a metal oxide material and hasan average particle diameter of 1.0 μm or less.

In the present invention, since the layer containing the blackbodymaterial is provided in the laminate film to form the package member forthe battery element, the heat dissipation characteristics by radiationcan be improved.

According to the present invention, an increase in temperature of thenonaqueous electrolyte battery can be suppressed, and the safety thereofcan be improved.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an exploded perspective view showing one structural example ofa nonaqueous electrolyte battery according to a first embodiment of thepresent invention;

FIG. 2 is a cross-sectional view showing one structural example of abattery element according to the first embodiment of the presentinvention;

FIG. 3 is a cross-sectional view showing one structural example of apackage member used for the nonaqueous electrolyte battery according tothe first embodiment of the present invention;

FIG. 4 is a cross-sectional view showing another structural example ofthe package member used for the nonaqueous electrolyte battery accordingto the first embodiment of the present invention;

FIG. 5 is a cross-sectional view showing another structural example ofthe package member used for the nonaqueous electrolyte battery accordingto the first embodiment of the present invention;

FIG. 6 is a cross-sectional view showing another structural example ofthe package member used for the nonaqueous electrolyte battery accordingto the first embodiment of the present invention;

FIG. 7 is a schematic perspective view showing one structural example ofa nonaqueous electrolyte battery according to a second embodiment of thepresent invention;

FIGS. 8A, 8B, and 8C are views showing one structural example of thenonaqueous electrolyte battery according to the second embodiment of thepresent invention;

FIG. 9 is a cross-sectional view showing one structural example of thenonaqueous electrolyte battery according to the second embodiment of thepresent invention; and

FIG. 10 is a schematic perspective view showing one structural exampleof the nonaqueous electrolyte battery according to the second embodimentof the present invention.

DETAILED DESCRIPTION

Hereinafter, the best mode (hereinafter referred to as “embodiment”) forcarrying out the present invention will be described.

(1) First Embodiment (example of a nonaqueous electrolyte batteryincluding a laminate film as a package member).

(2) Second Embodiment (example of a nonaqueous electrolyte batteryincluding a hard laminate film and a soft laminate film as a packagemember).

(1) First Embodiment (1-1) Structure of Nonaqueous Electrolyte Battery

First, the structure of a nonaqueous electrolyte battery according to afirst embodiment of the present invention will be described. FIG. 1 isan exploded perspective view showing the structure of a nonaqueouselectrolyte battery 20, and FIG. 2 is a cross-sectional view showing animportant portion of the nonaqueous electrolyte battery 20 shown in FIG.1 taken along the line II-II. The nonaqueous electrolyte battery 20described in this embodiment is a so-called lithium ion secondarybattery in which, for example, the capacity of a negative electrode isexpressed by a capacity component based on occlusion and release of alight metal (such as lithium).

As shown in FIG. 1, this nonaqueous electrolyte battery 20 has a thintype battery structure in which a battery element 10 provided with apositive electrode terminal 15A and a negative electrode terminal 15B isreceived between laminate films 17. The nonaqueous electrolyte battery20 is formed in such a way that the battery element 10 is packaged bybeing received in a battery element receiving portion 18, which is arecess portion formed by one laminate film 17 to receive a batteryelement, followed by sealing a peripheral portion of the battery element10. The laminate films 17 each have a heat fusion layer of a resinmaterial which faces the battery element 10. Subsequently, thetwo-layered laminate films 17 disposed so that the heat fusion layersthereof face each other are sandwiched with heat blocks of a metal orthe like; hence, the heat fusion layers of the laminate films 17 arefused so that the laminate films 17 are adhered to each other. Thedetailed structure of the laminate film 17 will be described later.

Structure of Battery Element

Hereinafter, the structure of the battery element 10 will be described.

As shown in the cross-sectional view of FIG. 2, in the battery element10 according to the first embodiment of the present invention, a beltshaped positive electrode 11, a separator 13, and a belt shaped negativeelectrode 12, and a separator 13 are laminated in this order and arewound in a longitudinal direction. In addition, the positive electrodeterminal 15A connected to the positive electrode 11 and the negativeelectrode terminal 15B connected to the negative electrode 12(hereinafter each referred to as “electrode terminal 15” unlessotherwise specifically indicated) are extended from the battery element10. Tight sealing members 16 which are each a sealing member to improveadhesiveness are provided at the positive and the negative electrodeterminals 15A and 15B at which the laminate films 17 are fused to eachother, the laminate films 17 each being used as a package member forpackaging the battery element 10. As the tight sealing member 16, forexample, a resin film formed of a polypropylene (PP) or the like may beused. In addition, a resin film of a modified resin material which has ahigh adhesiveness to the electrode terminal 15 made of a metal may alsobe used.

The positive electrode terminal 15A and the negative electrode terminal15B are, for example, both extended in the same direction from theinside to the outside of the laminate films 17. The positive electrodeterminal 15A is formed, for example, of a metal material, such asaluminum (Al), and has a thin-plate or a mesh structure. Aluminum (Al)is preferable since it is passivated so as not to be dissolved and hasan excellent electrical conductivity. The negative electrode terminal15B is formed, for example, of a metal material, such as copper (Cu),nickel (Ni), or stainless steel, and has a thin-plate or a meshstructure. Copper (Cu), nickel (Ni), stainless steel, or the like ispreferable since forming no alloy with lithium. Among these mentionedabove, copper is particularly preferable since having a high electricalconductivity.

Positive Electrode

The positive electrode 11 includes, for example, a positive electrodecollector 11A and positive electrode active material layers 11B providedon two surfaces thereof. The positive electrode collector 11A is formed,for example, of a metal material, such as aluminum (Al). The positiveelectrode active material layer 11B contains a positive electrode activematerial and a binder and whenever necessary, may further contain aconductive agent and the like.

The positive electrode active material contains at least one type ofpositive electrode material which is able to occlude and release lithiumfunctioning as an electrode reaction material and which has a reactionpotential, for example, of 3 to 4.5 V with respect to lithium. As thepositive electrode material described above, for example, a compositeoxide containing lithium may be mentioned. In particular, as a compositeoxide between lithium and a transition metal, lithium cobaltate (LiCoO₂)or lithium nickelate (LiNiO₂), each of which has a layered structure,may be used, or alternatively a solid solution containing the oxidementioned above (LiNi_(x)Co_(y)Mn_(z)O₂, in this formula, x, y, and zsatisfy 0<x<1, 0<y<1, 0<z<1, and x+y+z=1) may also be used.

In addition, as the positive electrode material, for example, lithiummanganate (LiMn₂O₄) having a spinel structure or a solid solutionthereof (Li(Mn_(2-v)Ni_(v))O₄, in this formula, v is less than 2) mayalso be used. Furthermore, as the positive electrode material, forexample, a phosphate compound, such as lithium iron phosphate (LiFePO₄),having an olivine structure may also be used. The reason for this isthat a high energy density can be obtained. In addition, as the positiveelectrode material, besides the materials mentioned above, for example,there may also be used an oxide, such as titanium oxide, vanadium oxide,or magnesium oxide; a disulfide, such as iron disulfide, titaniumdisulfide, or molybdenum disulfide; sulfur; or a conductive polymer,such as a polyaniline or a polythiophene.

As the positive electrode binder, a polymer containing vinylidenefluoride (VdF) as a component is contained. The reason for this is thatas in the case of an electrolyte layer 14, when vinylidene fluoride iscontained as one component, the adhesion of the electrolyte layer 14 tothe positive electrode 11 is improved. This polymer may be a homopolymer(poly(vinylidene fluoride)) or a copolymer containing vinylidenefluoride as one component. Although the content of the positiveelectrode binder in the positive electrode active material layer 11B isnot particularly limited, for example, the content is in the range of 1to 10 percent by weight. This content is preferably low when the weightaverage molecular weight of the polymer forming the positive electrodebinder is high, and on the other hand, the content is preferably highwhen the above weight average molecular weight is low. In addition, forexample, besides the polymer containing vinylidene fluoride as onecomponent, the binder may also include at least one of other polymersand copolymers. As the conductive agent, for example, carbon materials,such as graphite and acetylene black, may be mentioned.

Negative Electrode

The negative electrode 12 includes, for example, a negative electrodecollector 12A and negative electrode active material layers 12B providedon two surfaces thereof. The negative electrode collector 12A is formed,for example, of a metal material, such copper, nickel, or stainlesssteel. The negative electrode active material layer 12B contains anegative electrode active material and a negative electrode binder andwhenever necessary, may further contain a conductive agent (such as acarbon material) and the like.

The negative electrode active material contains at least one type ofnegative electrode material which is able to occlude and releaselithium. As this negative electrode material, for example, a carbonmaterial, a metal, a metal oxide, silicon, or a polymer material may bementioned. As the carbon material, for example, there may be used atleast one of a non-graphitizable carbon, an easy-graphitizable carbon,graphites, pyrolytic carbons, cokes, glassy carbons, a sintered organicpolymer compound, carbon fibers, and an active carbon. In particular,since having an excellent chemical stability, being capable of stablyrepeating an insertion/extraction reaction of lithium ions, and beingeasily commercially available, the graphites, such as a natural graphiteand an artificial graphite, have been widely used for lithium ionbatteries. In addition, as the types of graphites, for example, naturalgraphites and artificial graphites, such as mesophase carbon microbeads,carbon fibers, and cokes, may be mentioned. Since having a very smallchange in crystal structure caused by occlusion and release of lithiumand also functioning as a conductive agent, the carbon material ispreferably used.

In addition, as the negative electrode material, for example, there maybe mentioned a material containing at least one type of metal elementand half metal element as a constituent element, each of which iscapable of forming an alloy with lithium. This type of material ispreferable since a high energy density can be obtained. As this negativeelectrode material, an element, an alloy, or a compound of a metal or ahalf metal may be used, and a material at least partially containing atleast one phase of these mentioned above may also be used. In addition,as the alloy according to an embodiment of the present invention,besides an alloy formed of at least two metal elements, an alloy formedof at least one metal element and at least one half metal element mayalso be used. As a mater of course, the alloy may also include anon-metal element. In this texture, a solid solution, a eutectic crystal(eutectic mixture), an intermetallic compound, or a mixture of at leasttwo thereof may be present in some cases.

As the material containing at least one of a metal element and a halfmetal element as a constituent element, for example, materialscontaining silicon or tin may be mentioned. The reason for this is thatsince having a high capability of occluding and releasing lithium, thematerials mentioned above produce a high energy density. These materialsmay be used alone or in combination.

As the particular example of these materials, for example, a materialcontaining tin as a first constituent element and also containing asecond and a third constituent element is preferable, and in particular,a material (CoSnC material) containing tin, cobalt, and carbon asconstituent elements is preferable. The reason for this is thatexcellent cycle properties can be obtained as well as obtaining a highenergy density. This CoSnC-containing material may further containanother constituent element if necessary. The reason for this is thatthe battery capacity and the cycle properties are further improved.

In addition, as the particular example of the material mentioned above,for example, an element, an alloy, or a compound of tin, or an element,an alloy, or a compound of silicon may be mentioned. In this case, forexample, it is preferable that the negative electrode active materiallayer 12B is formed by a vapor phase method, a liquid phase method, aflame spray method, a firing method, or a method using at least two ofthese mentioned above and that the negative electrode active materiallayer 12B and the negative electrode collector 12A form an alloy at atleast part of the interface therebetween. The reasons for this are thatthe negative electrode active material layer 12B is not likely to befractured due to expansion and contraction caused by charge anddischarge and that the electron conductivity is improved between thenegative electrode collector 12A and the negative electrode activematerial layer 12B. As the vapor phase method, for example, a physicaldeposition method and a chemical deposition method may be mentioned, andmore particularly, there may be mentioned a vacuum deposition method, asputtering method, an ion plating method, a laser abrasion method, athermal chemical vapor deposition (CVD) method, or a plasma chemicalvapor deposition method. As the liquid phase method, a common method,such as electroplating or electroless plating, may be used. As thefiring method, for example, there may be mentioned a method in whichafter a negative electrode active material in the form of particles, abinder, and the like are mixed together and dispersed in a solvent, thedispersion thus obtained is applied, and a heat treatment is thenperformed at a temperature higher than a melting point of the negativeelectrode binder or the like. As the firing method, a common method mayalso be used, and for example, an atmosphere firing method, a reactivefiring method, or a hot press firing method may be mentioned.

As the negative electrode binder, for example, a poly(vinylidenefluoride) (PVdF) may be used.

In this secondary battery, since the charge capacity of the negativeelectrode active material is larger than that of the positive electrodeactive material, the relationship of the charge capacity between thepositive electrode 11 and the negative electrode 12 is adjusted so thata lithium metal is not deposited on the negative electrode 12 even in acompletely charged state.

Separator

The separator 13 separates the positive electrode 11 from the negativeelectrode 12 and allows lithium ions to pass through while preventingshort circuit caused by contact between the two electrodes. Thisseparator 13 is composed of a porous film of a synthetic resin, such asa polytetrafluoroethylene (PTFE), a polypropylene (PP), or apolyethylene (PE), or a porous film of a ceramic or the like. Theseparator 13 may be a laminate composed of at least two porous filmsmentioned above.

Electrolyte

The electrolyte layer 14 contains an electrolytic solution and aretainer containing a polymer compound which retains this electrolyticsolution, so that a so-called gel is formed. The electrolytic solutioncontains an electrolytic salt and a solvent dissolving this electrolyticsalt. As the electrolytic salt, a lithium salt may be used. As thelithium salt, for example, there may be mentioned an inorganic lithiumsalt, such as lithium hexafluorophosphate (LiPF₆), lithiumtetrafluoroborate (LiBF₄), lithium hexafluoroarsenate (LiAsF₆), lithiumhexafluoroantimonate (LiSbF₆), lithium perchlorate (LiClO₄), or lithiumtetrachloroaluminate (LiAlCl₄), or a perfluoroalkane sulfonic acidderivative, such as lithium trifluoromethanesulfonate (LiCF₃SO₃),lithium bis(trifluoromethanesulfonyle)imide (LiN(CF₃SO₂)₂), lithiumbis(pentafluoroethanesulfonyle)imide (LiN(C₂F₅SO₂)₂), or lithiumtris(trifluoromethanesulfonyle)methyde (LiC(CF₃SO₂)₃). These compoundsmentioned above may be used alone or in combination. Among thesementioned above, lithium hexafluorophosphate (LiPF₆) is preferable sincea high ion conductivity can be obtained and the cycle properties can beimproved.

As the solvent, a nonaqueous solvent may be used, and in particular, forexample, there may be used a lactone solvent, such as γ-butyrolactone,γ-valerolactone, δ-butyrolactone, or ε-caprolactone; a carbonatesolvent, such as ethylene carbonate, propylene carbonate, butylenecarbonate, vinylene carbonate, dimethyl carbonate, ethyl methylcarbonate, or diethyl carbonate; an ether solvent, such as1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane,tetrahydrofuran, or 2-methyl tetrahydrofuran; a nitrile solvent, such asacrylonitrile; a sulfolane solvent; phosphoric acids; a phosphoric acidester solvent; or pyrrolidones. As the solvent, these mentioned abovemay be used alone or in combination.

In addition, as the solvent, a compound in which hydrogen atoms of acyclic ester or a chain ester are partially or entirely replaced withfluorine is preferably contained. As this fluorinated compound,difluoroethylene carbonate (4,5-difluoro-1,3-dioxolane-2-on) ispreferably used. The reason for this is that even when a negativeelectrode 12 containing a compound of silicon (Si), tin (Sn), germanium(Ge), or the like as the negative electrode active material is used,charge/discharge cycle properties can be improved, and that inparticular, difluoroethylene carbonate has an excellent cyclecharacteristic improvement effect.

As the polymer compound, any compound which absorbs a solvent and turnsinto a gel may be used, and for example, there may be mentioned afluorinated polymer compound, such as poly(vinylidene fluoride) or acopolymer of vinylidene fluoride and hexafluoropropylene, an etherpolymer compound, such as a cross-linked compound containing apoly(ethylene oxide) or a poly(ethylene oxide), or a polymer compoundcontaining acrylonitrile, propylene oxide, or methyl methacrylate as arepeating unit. The polymer compounds mentioned above may be used aloneor in combination. In particular, in view of oxidation/reductionstability, a fluorinated polymer compound is preferable, and a copolymercontaining vinylidene fluoride and hexafluoropropylene as components isparticularly preferable.

Laminate Film

The laminate film 17 includes a metal foil and resin films provided ontwo surfaces thereof. In addition, the laminate film 17 has a layercontaining a blackbody material which has properties capable of usingblackbody radiation. Hereinafter, the laminate film will be described indetail.

As the laminate film 17, for example, a laminate film having an outerlayer film functioning as a protective layer, a metal foil, and an innerlayer film functioning as a heat fusion layer is used as a basisstructure. In addition, adhesive layers may be provided between theindividual layers. In the present invention, the laminate film 17further has a blackbody material layer containing the blackbody materialwhich has properties capable of using blackbody radiation, or theblackbody material is contained in at least one of the outer layer film,the inner layer film, and the adhesive layer. In addition, whenevernecessary, in order to impart additional properties, such as thestrength, to a package material, the structure in which an intermediateresin layer is provided between the outer layer and the metal foil orbetween the inner layer and the metal foil may also be used. In thiscase, the properties of the resin are not particularly limited, and inaccordance with the property to be desirably imparted to the packagematerial, resin properties (such as type of resin, mechanicalproperties, thickness, degree of crystallinity, and multilayer formationability) may be selected.

As the laminate film 17, for example, the following structures may bementioned.

(1) Outer layer film/blackbody material layer/adhesive layer/metalfoil/adhesive layer/inner layer film

(2) Outer layer film/adhesive layer/blackbody material layer/metalfoil/adhesive layer/inner layer film

(3) Outer layer film in which the blackbody material isdispersed/adhesive layer/metal foil/adhesive layer/inner layer film

(4) Outer layer film/adhesive layer in which the blackbody material isdispersed/metal foil/adhesive layer/inner layer film

(5) Outer layer film/blackbody material layer/outer layer film/adhesivelayer/metal foil/adhesive layer/inner layer film

(6) Outer layer film/adhesive layer/metal foil/adhesive layer/blackbodymaterial layer/inner layer film

(7) Outer layer film/adhesive layer/metal foil/blackbody materiallayer/adhesive layer/inner layer film

(8) Outer layer film/adhesive layer/metal foil/adhesive layer/innerlayer film in which the blackbody material is dispersed

(9) Outer layer film/adhesive layer/metal foil/adhesive layer in whichthe blackbody material is dispersed/inner layer film

This nonaqueous electrolyte battery 20 has, for example, the structurein which outer peripheral portions of two rectangular laminate films 17are fused to each other or adhered with an adhesive interposedtherebetween so that the inner layer films thereof face the batteryelement 10.

As the blackbody material having a black color, for example, there maybe used carbon materials, such as graphites and fullerenes, silicatesmaterials, and black metal oxide materials, such as an iron oxide(magnetite:triiron tetraoxide), a composite oxide of copper (Cu) andchromium (Cr), and a composite oxide of copper (Cu), chromium (Cr), zinc(Zn), and titanium (Ti). In particular, carbon black, graphite, anilineblack, iron black (FeOFe₂O₃), a chromite spinel solid solution, and thelike may be used. In addition, other materials having sufficientproperties capable of using blackbody radiation may also be used.

Incidentally, the black color indicates a color in which in the CMYcolor model, C (cyan), M (magenta), and Y (yellow) are all at 70 ormore.

The blackbody material preferably has a particle diameter of 1.0 μm orless and more preferably 0.5 μm or less. When the blackbody materiallayer is provided, by decreasing the thickness thereof as small aspossible, degradation in properties as the outer layer material can besuppressed. In addition, the radiation amount is proportional to thesurface area. By the reasons described above, the particle diameter ispreferably decreased.

Hereinafter, the individual structures will be described.

(a) The case in which the blackbody material layer is provided.

Hereinafter, the structure (such as (1), (2), (5), (6), or (7)) in whichthe blackbody material layer is provided will be described. For example,the structure (1) is shown in FIG. 3. As shown in FIG. 3, a laminatefilm 17 having the structure (1) includes a metal foil 17 a, an outerlayer film 17 b, an inner layer film 17 c, a blackbody material layer 17d, and adhesive layers 17 e.

The blackbody material layer 17 d includes the blackbody material and abase resin and independently has an emissivity of 0.6 or more. Additivesmay be added to the blackbody material layer 17 d if necessary. As thebase resin, for example, an acrylic resin, a urethane resin, or an epoxyresin may be used. As the additives, a curing agent, an antioxidant, andthe like may be used.

In addition, after a material containing the blackbody material isformed on the surface of an aluminum (Al) foil to have a thickness of 10μm, the emissivity of the surface of the blackbody material-containinglayer thus formed is measured by a reflection measurement method. Theemissivity is obtained in such a way that the reflectance is measured byobtaining the average reflection intensity in a wavelength region of 4to 24 μm (2,500 cm⁻¹ to 400 cm⁻¹) using a Fourier transformer infrared(FT-IR) spectrometer, and the emissivity (in the range of 0 to 1) wasobtained from the equation: (1-reflectance).

Incidentally, the emissivity is determined by the type of blackbodymaterial. In addition, when the blackbody material is formed from thesame material, although the emissivity is not changed by the change inthickness of a blackbody material-containing layer, the radiation amountis changed. Hence, the emissivity measured from a blackbodymaterial-containing layer having a thickness of 10 μm can be regarded tobe equivalent to the emissivity of a blackbody material-containing layerhaving a thickness of 2 μm as long as it contains the same blackbodymaterial as that of the above layer.

In addition, in order to suppress degradation in properties as thepackage member, the thickness of the blackbody material layer 17 d ispreferably set in the range of 1 to 10 μm. The blackbody material layer17 d is preferably formed as thin as possible while maintaining anemissivity of 0.6 or more.

The metal foil 17 a functions to protect the battery element 10 bypreventing invasion of moisture, oxygen, and light as well as to improvethe strength of the package member. As the metal foil 17 a, a soft metalmaterial is used, and for example, aluminum (Al), stainless steel (SUS),titanium (Ti), copper (Cu), or iron (Fe) plated with tin (Sn), zinc(Zn), or nickel (Ni) may be appropriately used. Among these mentionedabove, for example, aluminum processed by an annealing treatment (suchas JIS A8021P-O) or (JIS A8079P-O) is preferably used.

The thickness of the metal foil 17 a is preferably set in the range of50 to 150 μm. When the thickness is less than 50 μm, the materialstrength is degraded. On the other hand, when the thickness is more than150 μm, the workability is seriously degraded, and in addition, sincethe thickness of the laminate film 17 is increased, the volumeefficiency of the nonaqueous electrolyte battery 20 is degraded.

The outer layer film 17 b may have to have clean and fine appearance,toughness, flexibility, and the like, and for example, a nylon (Ny), apoly(ethylene terephthalate) (PET), a poly(ethylene naphthalate) (PEN),a poly(butylene terephthalate) (PET), or a poly(butylene naphthalate)(PBN) may be used.

The thickness of the outer layer film 17 b is preferably set in therange of 5 to 30 μm. When the thickness of the outer layer film is toolarge, the heat dissipation characteristics are degraded. On the otherhand, when the outer layer film is too small, the function as theprotective layer may be degraded in some cases.

Whenever necessary, letters, patterns, and the like may be drawn on theouter surface of the outer layer film 17 b. In addition, the blackbodymaterial layer 17 d may be formed by application on places other thanthose of the letters, patterns, and the like. Colors, shapes, andarrangement of the letters, patterns, and the like are not particularlylimited, and the letters and patterns may not be concentrated on a partof the outer surface. Regardless of modes of the letters and patterns,the heat dissipation effect can be obtained proportional to the area ofthe blackbody material exposed at the outer surface. The letters andpatterns are necessarily designed in consideration of the heatdissipation effect.

The inner layer films 17C are films melted by heat and/or ultrasonicwaves and are fused to each other, and for example, a polyethylene (PE),a polypropylene (PP), a cast polypropylene (CPP), or a poly(ethyleneterephthalate) (PET) may be used. In addition, a plurality of thepolymers mentioned above may be selected and used. As the polyethylene(PE), a low-density polyethylene (LDPE), a high-density polyethylene(HDPE), a linear low-density polyethylene (LLDPE) may be used.

The thickness of the inner layer film 17 c is preferably set in therange of 10 to 50 μm. When the inner layer film 17 c is too thick, therate of heat conduction from the battery element 10 to the metal foil 17a is low, and hence the heat dissipation characteristics are degraded.In addition, when the inner layer film 17 c is too thin, the sealingproperties are degraded when the battery element 10 is sealed bypackaging.

As an adhesive material used for the adhesive layer 17 e, an adhesive ofa urethane resin, an acrylic resin, a styrene resin, or the like may beused, which has been used for forming a laminate film. In addition, whena resin material having a heat adhesion effect to a metal is used,direct adhesion may be performed by a heat roller, and bonding may alsobe performed by coating of a resin material melted or diluted with asolvent using extrusion or the like.

In the structure in which the blackbody material layer 17 d is provided,since the blackbody material layer 17 d is simply provided in a relatedbasic structure, the difference in properties from the basic structureis small, and hence the production and the use thereof are easilycarried out. In addition, the adhesive layer 17 e may not be used insome cases and may be used if necessary for a laminate formation.

(b) The case in which an outer layer film containing the blackbodymaterial dispersed therein is used.

Hereinafter, the structure (such as (3)) using an outer layer film inwhich the blackbody material is dispersed will be described. Thestructure (3) is shown in FIG. 4. As shown in FIG. 4, a laminate film 17having a structure as that of (3) includes the metal foil 17 a, an outerlayer film 17 b′ in which the blackbody material is dispersed, the innerlayer film 17 c, and the adhesive layers 17 e.

As the outer layer film 17 b′ in which the blackbody material isdispersed, for example, a film formed by dispersing the blackbodymaterial in a material, such as a nylon (Ny), a poly(ethyleneterephthalate) (PET), a poly(ethylene naphthalate) (PEN), apoly(butylene terephthalate) (PBT), or a poly(butylene naphthalate)(PBN), may be used.

In this case, the outer layer film 17 b′ independently has an emissivityof 0.6 or more. The content of the blackbody material in the outer layerfilm 17 b′ is preferably in the range of 50 to 80 percent by weight ormore of the outer layer film 17 b′. When the content of the blackbodymaterial is too low, the heat dissipation characteristics are degraded.On the other hand, when the content of the blackbody material is toohigh, the strength and the function of the outer layer film may bedegraded in some cases.

In addition, except that the outer layer film 17 b′ in which theblackbody material is dispersed is used, and that the blackbody materiallayer is not provided, the structure similar to that of the (a) may beformed. In addition, the adhesive layer 17 e may not be necessary insome cases and may be used if necessary for laminate formation.

(c) The case in which an inner layer film containing the blackbodymaterial dispersed therein is used.

Hereinafter, the structure (such as (8)) using an inner layer film inwhich the blackbody material is dispersed will be described. Thestructure (8) is shown in FIG. 5. As shown in FIG. 5, a laminate film 17having a structure as that of (8) includes the metal foil 17 a, theouter layer film 17 b, and an inner layer film 17 c′ in which theblackbody material is dispersed, and the adhesive layers 17 e.

As the inner layer film 17 c′ in which the blackbody material isdispersed, a film formed by dispersing the blackbody material in amaterial, such as a polypropylene (PP), a cast polypropylene (CPP), apoly(ethylene terephthalate) (PET), a low-density polyethylene (LDPE), ahigh-density polyethylene (HDPE), or a linear low-density polyethylene(LLDPE), may be used.

In this case, the inner layer film 17 c′ independently has an emissivityof 0.6 or more. The content of the blackbody material in the inner layerfilm 17 c′ is preferably in the range of 60 to 80 percent by weight ofthe inner layer film. When the content of the blackbody material is toolow, the heat dissipation characteristics are degraded. In addition,when the content of the blackbody material is too high, the strength andthe function of the inner layer film may be degraded in some cases.

In addition, except that the inner layer film 17 c′ in which theblackbody material is dispersed is used, and that the blackbody materiallayer 17 d is not provided, the structure similar to that of the (a) maybe formed. In addition, the adhesive layer 17 e may not be used in somecases and may be used if necessary for laminate formation.

(d) The case in which an adhesive layer containing the blackbodymaterial dispersed therein is used.

Hereinafter, the structure (such as (4) or (9)) using an adhesive layerin which the blackbody material is dispersed will be described. As oneexample, the structure (4) is shown in FIG. 6. As shown in FIG. 6, alaminate film 17 having a structure as that of (4) includes the metalfoil 17 a, the outer layer film 17 b, the inner layer film 17 c, andadhesive layers 17 e′ in which the blackbody material is dispersed.

The adhesive layer 17 e′ in which the blackbody material is dispersedmay be formed of an adhesive layer in which the blackbody material isdispersed in a material, such as a urethane resin, an acrylic resin, ora styrene resin. In this case, the adhesive layer 17 e′ independentlyhas an emissivity of 0.6 or more. The content of the blackbody materialin the adhesive layer 17 e′ is preferably in the range of 60 to 80percent by weight of the adhesive layer 17 e′. When the content of theblackbody material is too low, the heat dissipation characteristics aredegraded. In addition, when the content of the blackbody material is toohigh, the function of the adhesive layer may be degraded in some cases.

Except that the adhesive layer 17 e′ in which the blackbody material isdispersed is formed, and that the blackbody material layer is notprovided, the structure similar to that of the (a) may be formed.

As described above, since the laminate film 17 which has the layercontaining the blackbody material is used, the heat dissipation effectof dissipating heat to the outside by using the blackbody radiation canbe enhanced. In addition, in the above structures (1) to (9), thestructures (1) to (5) in which the layer containing the blackbodymaterial is provided outside the metal foil 17 a (in a direction to theoutside of the battery when the battery element 10 is packaged) is morepreferable. The reason for this is believed that when the layercontaining the blackbody material is provided outside the metal foil,the time necessary to propagate released heat to the outer surface canbe decreased.

In addition, when the layer containing the blackbody material isprovided outside the metal foil, the appearance of the laminate film 17at an outer layer film side can be made black. Accordingly, pin holesand cracks generated in the laminate film 17 can be easily detected;hence, it is more preferable.

(1-2) Method for Manufacturing Nonaqueous Electrolyte Battery

This nonaqueous electrolyte battery 20 can be manufactured, for example,by the following procedure.

Formation of Positive Electrode

The positive electrode active material, the binder, and the conductiveagent are uniformly mixed together to form a positive electrode mixture,and this positive electrode mixture is dispersed in a solvent to form aslurry. In this case, as long as the positive electrode active material,the binder, and the conductive agent are uniformly mixed together, themixing ratio therebetween is not particularly limited. Next, after thisslurry is uniformly applied on the positive electrode collector 11A by adoctor blade method or the like, the solvent is removed by compressionand drying performed by a roll press machine or the like at a hightemperature, so that the positive electrode active material layers 11Bare formed. The positive electrode active material layers 11B areprovided, for example, on two surfaces of the positive electrodecollector 11A. In accordance with the structure of the battery element10, the positive electrode active material layer 11B may be provided onone surface of the positive electrode collector 11A. In addition, as thesolvent, for example, N-methyl-2-pyrrolidone may be used. Finally, thepositive electrode terminal 15A is fitted on the positive electrodecollector 11A at which the positive electrode active material layer 11Bis not formed.

Formation of Negative Electrode

The negative electrode active material and the binder composed of atwo-component copolymer are uniformly mixed together to form a negativeelectrode mixture, and this negative electrode mixture is dispersed in asolvent to form a slurry. In this case, as long as the negativeelectrode active material and the binder are uniformly mixed together,the mixing ratio therebetween is not particularly limited. In addition,the conductive agent may be added if necessary. Next, after this slurryis uniformly applied on the negative electrode collector by a doctorblade method or the like, the solvent is removed by compression anddrying performed by a roll press machine or the like at a hightemperature, so that the negative electrode active material layer isformed. As in the structure of the positive electrode 11, the negativeelectrode active material layer 12B may be provided on at least onesurface of the negative electrode collector 12A. Finally, the negativeelectrode terminal 15B is fitted on the negative electrode collector 12Aat which the negative electrode active material layer 12B is not formed.

Formation of Battery Element

The gel electrolyte layers 14 are formed on the surface of the positiveelectrode active material layer 11B of the positive electrode 11 thusformed and the surface of the negative electrode active material layer12B of the negative electrode 12 thus formed. First, a sol precursorsolution containing an electrolyte, a polymer compound, and a dilutingsolvent is prepared. As the polymer compound, a material composed of athree-component copolymer is used. Next, the sol precursor solution isapplied to the respective surfaces of the positive electrode activematerial layer 11B and the negative electrode active material layer 12B,and subsequently, the diluting solution in the precursor solution isevaporated. As a result, the gel electrolyte layers 14 are formed.

Subsequently, the positive electrode 11 provided with the electrolytelayer 14 and the negative electrode 12 provided with the electrolytelayer 14 are laminated with the separators 13 interposed therebetweenand are wound in a longitudinal direction. In this stage, by aprotective tape 19, the electrodes and the like thus wound are fixed.Accordingly, the battery element 10 is formed.

Formation of Laminate Film

(a) The case in which the blackbody material layer is provided.

The blackbody material layer 17 d is formed, for example, by applying orspraying a paint containing the blackbody material, a base resin, and asolvent on the outer layer film 17 b, the inner layer film 17 c, or themetal foil 17 a, followed by removing the solvent. As the solvent usedin this case, for example, toluene, ethyl acetate, xylene, and2-butanone may be used.

Subsequently, the outer layer film 17 b, the metal foil 17 a, and theinner layer film 17 c are adhered to each other, for example, with theadhesive layers 17 e provided therebetween to form the laminate film 17.In this stage, the blackbody material layer 17 d formed on one surfaceof the outer layer film 17 b, the metal foil 17 a, or the inner layerfilm 17 c is controlled so as to be placed at a desired position.

(b) The case in which the outer layer film containing the blackbodymaterial dispersed therein is used.

When the outer layer film 17 b′ is formed, the blackbody material ismixed in a film material to form the outer layer film 17 b′.Subsequently, the outer layer film 17 b′, the metal foil 17 a, and theinner layer film 17 c are adhered to each other with the adhesive layers17 e interposed therebetween, so that the laminate film 17 is formed.

(c) The case in which the inner layer film containing the blackbodymaterial dispersed therein is used.

When the inner layer film 17 c′ is formed, the blackbody material ismixed in a film material to form the inner layer film 17 c′.Subsequently, the outer layer film 17 b, the metal foil 17 a, and theinner layer film 17 c′ are adhered to each other with the adhesivelayers 17 e interposed therebetween, so that the laminate film 17 isformed.

(d) The case in which the adhesive layer containing the blackbodymaterial dispersed therein is used.

By using an adhesive containing the blackbody material, the outer layerfilm 17 b, the metal foil 17 a, and the inner layer film 17 c areadhered to each other with the adhesive layers 17 e′ interposedtherebetween, so that the laminate film 17 is formed.

Subsequently, the battery element receiving portion 18 is formed by thelaminate film 17 using deep drawing from an inner layer film 17 c sideto an outer layer film 17 b side. In addition, after the battery element10 is received in the battery element receiving portion 18 and ispackaged by the laminate film 17, the peripheral portions of thelaminate films 17 are adhered to each other by heat fusion or the like,so that the battery element 10 is sealed. In this stage, the tightsealing members 16 are provided at the positive electrode terminal 15Aand the negative electrode terminal 15B at which the laminate films 17are fused to each other. Accordingly, the nonaqueous electrolyte battery20 shown in FIGS. 1 and 2 is completed.

(2) Second Embodiment (2-1) Structure of Nonaqueous Electrolyte Battery

In the second embodiment, by using the battery element 10 similar tothat in the first embodiment, a nonaqueous electrolyte battery 30 inwhich the battery element 10 is packaged with a hard laminate film and asoft laminate film will be described. In this second embodiment,description of structural portions similar to those of the firstembodiment will be omitted.

In the second embodiment, a battery element packaged by a hard laminatefilm and a soft laminate film is called a nonaqueous electrolytebattery, and the nonaqueous electrolyte battery which is connected to acircuit substrate and which is fitted with a top cover and a rear coveris called a battery pack. In the battery pack and the nonaqueouselectrolyte battery, a positive and a negative electrode terminal sideis called a top portion, the side opposite to the top portion is calleda bottom portion, and the others are called a side portion. In addition,the length in a side portion direction is called the width, and thelength in a top portion-bottom portion direction is called the height.

(2-2) Structure of Battery Pack

FIG. 7 shows one structural example of a battery pack 40 according tothe second embodiment of the present invention. The battery pack 40 is,for example, a battery pack of a lithium ion polymer secondary batteryhaving a rectangular or a flat shape. As shown in FIG. 7, this batterypack 40 includes the nonaqueous electrolyte battery 30 having twoopenings at two ends thereof in which the battery element 10 is receivedin a package member, a top cover 25 a, and a bottom cover 25 b, thesecovers being fitted to the respective openings at the two ends of thenonaqueous electrolyte battery 30.

FIG. 8 shows the nonaqueous electrolyte battery 30 according to thesecond embodiment in process of manufacturing. The package member has aplate shape as a whole and includes a hard laminate film 26 having arectangular shape when viewed in a plane direction and a soft laminatefilm 27 having a rectangular shape, the length of which in a heightdirection is shorter than that of the hard laminate film 26. Theopenings at the two ends of the nonaqueous electrolyte battery 30 eachhave a rectangular shape as a whole, and the two short sides thereofeach protrude outside so as to form an oval arc.

The nonaqueous electrolyte battery 30 includes the soft laminate film 27having a battery element receiving portion 28, the battery element 10received in the battery element receiving portion 28, and the hardlaminate film 26 provided so as to cover the opening of the batteryelement receiving portion 28 which receives the battery element 10.

In addition, from a sealing portion at which the hard laminate film 26and the soft laminate film 27 are sealed to each other, the positiveelectrode terminal 15A and the negative electrode terminal 15Belectrically connected to the positive electrode and the negativeelectrode, respectively, of the battery element 10 are extended.

The top cover 25 a and the bottom cover 25 b have shapes fittable to therespective openings at the two ends of the nonaqueous electrolytebattery 30. In particular, when viewed from a front surface, the coverseach have a rectangular shape as a whole, and the two short sides ofeach cover protrude outside so as to form an oval arc. In addition, thefront surface indicates a direction when the nonaqueous electrolytebattery 30 is viewed from a top portion side.

Hereinafter, with reference to FIGS. 7 to 10, the package member, thecircuit substrate, the top cover 25 a, and the bottom cover 25 b will bedescribed.

Package Member

As shown in FIGS. 7 and 8, this package member includes the softlaminate film 27 having the battery element receiving portion 28 inwhich the battery element 10 is received and the hard laminate film 26provided on the soft laminate film 27 to cover the battery elementreceiving portion 28.

Hereinafter, the hard laminate film 26 will be described.

The hard laminate film 26 is rectangular and has a top long side 36 aand a bottom long side 36 b, the lengths of which are equal to eachother, and two short sides 36 c and 36 d, the lengths of which are equalto each other. As shown in FIG. 9, in the state when the hard laminatefilm 26 wraps around the battery element receiving portion 28 in whichthe battery element 10 is received, the lengths of the top long side 36a and the bottom long side 36 b of the hard laminate film 26 aredesigned so that the two short sides 36 c and 36 d come into contactwith each other or face each other with a slight gap providedtherebetween.

In addition, the top long side 36 a of the hard laminate film 26 may beprovided with notch portions 38 as shown in FIG. 8. As shown in FIG. 7,the notch portions 38 are provided so as to be located at the two shortsides of the nonaqueous electrolyte battery 30 when viewed from thefront surface. Since the notch portions 38 are provided, fitting of thetop cover 25 a can be easily performed.

The hard laminate film 26 has the same structure as that of the laminatefilm 17 except that a metal foil 26 a is a hard metal foil. That is, thehard laminate film 26 at least includes the metal foil 26 a, an outerlayer film 26 b, and an inner layer film 26 c, and for example, as inthe above (1), a blackbody material layer 26 d is provided. In addition,as in the laminate film 17, the structure similar to that of one of theabove (2) to (9) may also be formed.

The metal foil 26 a of the hard laminate film 26 functions to maintainthe shape after being bent and to withstand against deformation causedby an external force, and a hard metal material, such as aluminum (Al),stainless steel (SUS), iron (Fe), copper (Cu), or nickel (Ni), may beappropriately used. Among these mentioned above, aluminum (Al) andstainless steel (SUS) are most preferable, and in particular, forexample, hard aluminum (JIS A3003P-H18) or (JIS A3004P-H18) withoutbeing processed by an annealing treatment or austenite stainless steel(SUS304) is preferably used.

The thickness of the metal foil 26 a is preferably set in the range of50 to 150 μm. When the thickness is less than 50 μm, the materialstrength is degraded. On the other hand, when the thickness is more than150 μm, the workability is seriously degraded, and in addition, sincethe thickness of the hard laminate film 26 is increased, the volumeefficiency of the battery pack 40 is degraded.

Hereinafter, the soft laminate film 27 will be described.

The lamination structure of the soft laminate film 27 is set similar tothat of the laminate film 17. That is, the soft laminate film 27 atleast includes a metal foil 27 a, an outer layer film 27 b, and an innerlayer film 27 c, and for example, as the structure of the above (1), ablackbody material layer 27 d is provided. In addition, as in thelaminate film 17, the structure similar to that of one of the above (2)to (9) may also be formed.

The soft laminate film 27 is rectangular and has a top long side 37 aand a bottom long side 37 b, the lengths of which are equal to eachother, and two short sides 37 c and 37 d, the lengths of which are equalto each other, and at a central portion of the soft laminate film 27,the battery element receiving portion 28 receiving the battery element10 is formed by drawing or the like. The lengths of the top long side 37a and the bottom long side 37 b of the soft laminate film 27 are setlarger than the width of the battery element receiving portion 28 inwhich the battery element 10 is received. In addition, according to thisembodiment, the two facing sides of the soft laminate film 27 at the topand the bottom sides are each used as the long side, and the two facingsides orthogonal thereto are each used as the short side; however,depending on the shape of the battery element 10, the top and the bottomsides may be used as the short side, and the sides orthogonal theretomay be used as the long side.

In addition, the two short sides 37 c and 37 d of the soft laminate film27 are set slightly smaller than the short sides 36 c and 36 d of thehard laminate film 26. Accordingly, the soft laminate film 27 can belaminated on the hard laminate film 26 so that at the top and the bottomsides of the nonaqueous electrolyte battery 30, only the hard laminatefilm 26 exists. At a portion at which only the hard laminate film 26exists, the inner layer film 26 c thereof is exposed; hence, when thetop cover 25 a and the bottom cover 25 b are fitted, the inner layerfilm 26 c can be adhered to the top cover 25 a and the bottom cover 25 bby heat fusion.

Circuit Substrate

A circuit substrate 34 is a substrate to which the positive electrodeterminal 15A and the negative electrode terminal 15B of the batteryelement 10 are electrically connected. On the circuit substrate 34,besides a protective circuit including temperature protective elements,such as a fuse, a positive temperature coefficient (PCT) element, and athermistor, for example, an ID resistor for discriminating a batterypack is mounted, and a plurality (such as three) of connection portionsare further formed. In the protective circuit, charge and dischargecontrol field effect transistors (FET), an integrated circuit (IC) formonitoring the battery element 10 and controlling the charge anddischarge control FETs, and the like are provided.

The PCT element is connected to the battery element 10 in series, andwhen the temperature of the battery is increased higher than a settemperature, the electrical resistance of the PCT element is rapidlyincreased, so that the flow of current through the battery ispractically stopped. The fuse is also connected to the battery element10 in series, and when an overcurrent flows through the battery, thefuse is melted down by the current flowing therethrough, so that theflow of current is stopped. In addition, the fuse is provided with aheater resistor in the vicinity thereof, and since the temperature ofthe heater resistor is increased in overvoltage, meltdown of the fuseoccurs, so that the flow of current is stopped.

In addition, when a terminal voltage of the battery element 10 is morethan 4.3 to 4.4 V, hazardous events, such as heat generation andignition, may occur in some cases. Hence, the protective circuitmonitors the voltage of the battery element 10, and in an overchargestate in which the voltage is more than 4.3 to 4.4 V, the charge controlFET is set in an OFF state, so that the charge is inhibited.Furthermore, when the terminal voltage of the battery element 10 isover-discharged to a discharge inhibition voltage or less, and when thevoltage of the battery element 10 becomes 0 V, the battery element 10 isin an inside short-circuit state, and as a result, recharge may not beperformed in some cases. Hence, the voltage of the battery element 10 ismonitored, and when the battery element 10 is placed in anover-discharge state, the discharge control FET is set in an OFF state,so that the discharge is inhibited.

Top Cover

The top cover 25 a is to be fitted to the top side opening of thenonaqueous electrolyte battery 30 and has a rectangular shape as a wholewhen viewed in a front surface direction, and the two short sides of thetop cover 25 a each expand outside so as to form an oval arc. A sidewall to be fitted to the top side opening is provided on the surface ofthe top cover 25 a at the side of the battery element 10. This side wallis provided partially or entirely along the periphery of the top cover25 a and is adhered to the end portion of the hard laminate film 26 byheat fusion.

The circuit substrate 34 is received in the top cover 25 a. In order toexpose a plurality of contact points of the circuit substrate 34 to theoutside, a plurality of openings is provided in the top cover 25 a atpositions corresponding to the contact points. The contact points of thecircuit substrate 34 are brought into contact with an electronic devicethrough the openings in the top cover 25 a. Accordingly, the batterypack 40 and the electronic device are electrically connected to eachother. The top cover 25 a as described above is formed by injectionmolding in advance.

Bottom Cover

The bottom cover 25 b is to be fitted to the bottom side opening of thenonaqueous electrolyte battery 30 and has a rectangular shape as a wholewhen viewed in a front surface direction, and the two short sides of thebottom cover 25 b each expand outside so as to form an oval arc. A sidewall to be fitted to the bottom side opening is provided on the surfaceof the bottom cover 25 b at the side of the battery element 10. Thisside wall is provided partially or entirely along the periphery of thebottom cover 25 b and is adhered to the end portion of the hard laminatefilm 26 by heat fusion.

At least one penetrating hole and preferably at least two penetratingholes may be provided in the bottom cover 25 b from the surface facingthe battery element 10 to the surface opposite thereto. In this case,when a hot melt resin is charge through the penetrating hole, thenonaqueous electrolyte battery 30 and the bottom cover 25 b can be moretightly adhered to each other. If at least two penetrating holes areprovided, when a resin is charged, at least one penetrating hole can beused to remove air present between the battery element 10 and the bottomcover 25 b, and hence filling properties of the resin can be improved.

The bottom cover 25 b as described above is formed by injection moldingin advance. In addition, a method for molding the bottom cover 25 bintegral with the nonaqueous electrolyte battery 30 may also be used inwhich the nonaqueous electrolyte battery 30 is placed in a mold, and ahot melt resin is charged in a bottom portion thereof.

(2-3) Method for Forming Battery Pack

Hereinafter, a method for manufacturing the battery pack 40 will bedescribed.

Formation of Battery Element

The battery element 10 can be formed in a manner similar to that of thefirst embodiment.

Next, as shown in FIGS. 9 and 10, the inner layer film 26 c of the hardlaminate film 26 and the inner layer film 27 c of the soft laminate film27 are disposed so as to face each other. In addition, after the batteryelement 10 is received in the battery element receiving portion 28, thehard laminate film 26 is overlapped on the soft laminate film 27 so asto cover the opening of the battery element receiving portion 28.Subsequently, an overlapped portion between the hard laminate film 26and the soft laminate film 27 is sealed along the periphery of thebattery element receiving portion 28. The sealing is performed using ametal heater head (not shown) to heat-fuse the inner layer film 26 c ofthe hard laminate film 26 and the inner layer film 27 c of the softlaminate film 27 under evacuation conditions.

Next, as shown in FIG. 9, the hard laminate film 26 is deformed so thatthe short sides 36 c and 36 d thereof come into contact with each other.In this case, since an adhesive film 29 is provided on the outsidesurface of the bottom portion of the battery element receiving portion28 provided in the soft laminate film 27 at which the short sides 37 cand 37 d of the deformed soft laminate film 27 face each other and isthen heated by a heater head, parts of the outer layer film 27 b of thesoft laminate film 27 are adhered to each other, thereby forming thenonaqueous electrolyte battery 30. When an unnecessarily hightemperature is applied to the battery element 10, the battery element 10may be damaged thereby. Hence, the temperature of the heater head is setso as to melt a resin material of the adhesive film 29. The adhesivefilm 29 is preferably formed of a material to be melted at a temperatureat which the battery element 10 is not damaged.

Formation of Battery Pack

Next, as shown in FIG. 7, after the positive electrode terminal 15A andthe negative electrode terminal 15B are connected to the circuitsubstrate 34, the circuit substrate 34 is received in the top cover 25 ausing a holder 25 c molded so as to be fittable thereto. In addition,after the holder 25 c is arranged to be located at a nonaqueouselectrolyte battery 30 side, the top cover 25 a is fitted to the topside opening of the nonaqueous electrolyte battery 30. In addition, thebottom cover 25 b is fitted to the bottom side opening of the nonaqueouselectrolyte battery 30.

Finally, the fitted portions of the top cover 25 a and the bottom cover25 b are heated by a heater head, so that the top cover 25 a and thebottom cover 25 b are adhered to the inner layer film 26 c of the hardlaminate film 26. As a result, the battery pack 40 having the appearanceshown in FIG. 10 is formed.

As described in the second embodiment, when the layers containing theblackbody material are provided in the hard laminate film 26 and thesoft laminate film 27, in the battery pack according to the secondembodiment, the heat dissipation characteristics can also be improved.

EXAMPLES

Hereinafter, particular examples of the present invention will bedescribed in detail; however, the present invention is not limitedthereto.

As the laminate film used in the following examples, one of the laminatefilms having the structures (1) to (9) was used.

(1) Outer layer film/blackbody material layer/adhesive layer/metalfoil/adhesive layer/inner layer film

(2) Outer layer film/adhesive layer/blackbody material layer/metalfoil/adhesive layer/inner layer film

(3) Outer layer film in which the blackbody material isdispersed/adhesive layer/metal foil/adhesive layer/inner layer film

(4) Outer layer film/adhesive layer in which the blackbody material isdispersed/metal foil/adhesive layer/inner layer film

(5) Outer layer film/blackbody material layer/outer layer film/adhesivelayer/metal foil/adhesive layer/inner layer film

(6) Outer layer film/adhesive layer/metal foil/adhesive layer/blackbodymaterial layer/inner layer film

(7) Outer layer film/adhesive layer/metal foil/blackbody materiallayer/adhesive layer/inner layer film

(8) Outer layer film/adhesive layer/metal foil/adhesive layer/innerlayer film in which the blackbody material is dispersed

(9) Outer layer film/adhesive layer/metal foil/adhesive layer in whichthe blackbody material is dispersed/inner layer film

(Basic structure) Outer layer film/adhesive layer/metal foil/adhesivelayer/inner layer film

Example 1

In Example 1, a battery pack was formed using a laminate film formed bychanging the blackbody material, and a battery surface temperature inhigh-temperature storage was measured.

Example 1-1 Formation of Positive Electrode

After 92 percent by weight of lithium cobaltate (LiCoO2), 3 percent byweight of a powdered poly(vinylidene fluoride), and 5 percent by weightof a powdered graphite were uniformly mixed together, the mixture thusformed was dispersed in N-methyl-2-pyrrolidone, so that a positiveelectrode mixture in the form of slurry was prepared. This positiveelectrode mixture was uniformly applied to two surfaces of an aluminumfoil to be used as a positive electrode collector, followed by vacuumdrying at 100° C. for 24 hours, thereby forming a positive electrodeactive material layer.

Subsequently, after the positive electrode active material layer waspress-molded by a roll press machine to form a positive electrode sheet,the positive electrode sheet was cut into a belt shape as a positiveelectrode, and a positive electrode terminal made of an aluminum filmwas welded thereto at a position at which the active material was notapplied. Furthermore, a tight adhesion member made of a polypropyleneresin film was adhered to the positive electrode terminal at which heatfusion layers of laminate films face each other when package isperformed thereby.

Formation of Negative Electrode

After 91 percent by weight of an artificial graphite and 9 percent byweight of a powdered poly(vinylidene fluoride) were uniformly mixedtogether, the mixture thus formed was dispersed inN-methyl-2-pyrrolidone, so that a negative electrode mixture in the formof slurry was prepared. This negative electrode mixture was uniformlyapplied to two surfaces of a copper foil to be used as a negativeelectrode collector, followed by vacuum drying at 120° C. for 24 hours,thereby forming a negative electrode active material layer.

Subsequently, after the negative electrode active material layer thusformed was press-molded by a roll press machine to form a negativeelectrode sheet, the negative electrode sheet was cut into a belt shapeas a negative electrode, and a negative electrode terminal made of anickel foil was welded thereto at a position at which the activematerial was not applied. Furthermore, a sealant made of a polypropyleneresin film was adhered to the negative electrode terminal at which theheat fusion layers of the laminate films face each other when package isperformed thereby.

Formation of Electrolyte

Ethylene carbonate (EC) and propylene carbonate (PC) were mixed togetherat a weight ratio of 6:4 and were then dissolved in LiPF64 at aconcentration of 0.8 mol/Kg, so that an electrolyte was formed. As amatrix polymer to be dispersed in this electrolyte, a copolymer whichwas obtained by polymerizing hexafluoropropylene (HFP) at aconcentration of 7 percent by weight with respect to vinylidene fluoride(VdF) was used.

The matrix polymer described above, the electrolyte, and a dilutingsolvent were mixed together at a weight ratio of 1:10:10, so that aprecursor solution in the form of a sol was formed. As the dilutingsolution, dimethyl carbonate (DMC) was used. After this sol precursorsolution was applied on the positive electrode active material layer andthe negative electrode active material layer, the diluting solution wasevaporated at a temperature of 100° C., so that gel electrolyte layerseach having a thickness of 15 μm were formed on the positive electrodeand the negative electrode.

Formation of Laminate Film

As shown in the above (1), a laminate film having a structure of anouter layer film/blackbody material layer/adhesive layer/metalfoil/adhesive layer/inner layer film was formed. In this case, as themetal foil, an aluminum foil having a thickness of 50 μm was used, andas the inner layer film, a polypropylene (PP) having a thickness of 30μm was used.

In addition, as the outer layer film, there was used a film in which ablackbody material layer was provided on a metal foil-side surface of apoly(ethylene terephthalate) having a thickness of 30 μm. The blackbodymaterial layer was formed to have a thickness of 2.0 μm by applying ablackbody solution in which 70 percent by weight of a carbon blackhaving an average particle diameter D50 of 0.5 μm functioning as theblackbody material and 30 percent by weight of an acrylic resin weremixed together to one surface of the outer layer film.

In this case, the blackbody material layer was formed on the surface ofan aluminum foil to have a thickness of 10 μm, and the emissivity of thesurface of the blackbody material layer was obtained by a reflectionmeasurement method. The emissivity was obtained in such a way that thereflectance was measured by obtaining the average reflection intensityin the wavelength region of 4 to 24 μm (2,500 cm-1 to 400 cm-1) using aFourier transformer infrared (FT-IR) spectrometer, and the emissivity(in the range of 0 to 1) was obtained from the equation:(1-reflectance). In Example 1-1, the emissivity was 0.82.

The outer layer film provided with the blackbody material layer and theinner layer film were adhered to the metal foil with adhesive layerseach having a thickness of 5 μm therebetween. In this case, theblackbody material layer provided on the outer layer film was arrangedto be located at a metal foil side.

Assembly of Nonaqueous Electrolyte Battery

The positive electrode and the negative electrode each provided with thegel electrolyte layer were laminated and wound with porous polyethyleneseparators interposed therebetween, so that a flat battery element wasformed. In this case, a battery element having a height of 60 mm, awidth of 40 mm, and a thickness of 5 mm was formed to have a dischargecapacity of 900 mAh when the full charge voltage and the discharge endvoltage were set to 4.2 V and 3.0 V, respectively. This battery elementwas packaged by a package member composed of aluminum laminate filmsusing carbon black as the above blackbody material. After the batteryelement was received in the recess portion formed in the aluminumlaminate film and was packaged, individual sides of the laminates filmsalong the periphery of the battery element were adhered to each other byheat fusion and vacuum-sealed, so that a test battery was formed.

Example 1-2

Except that when the laminate film was formed, graphite was used as theblackbody material, a test battery was formed in a manner similar tothat of Example 1-1. In addition, when the emissivity of the blackbodymaterial layer using graphite was measured as in Example 1-1, theemissivity was 0.85.

Example 1-3

Except that when the laminate film was formed, iron black (FeOFe₂O₃) wasused as the blackbody material, a test battery was formed in a mannersimilar to that of Example 1-1. In addition, when the emissivity of theblackbody material layer using iron black (FeOFe₂O₃) was measured as inExample 1-1, the emissivity was 0.79.

Example 1-4

Except that when the laminate film was formed, a chromite spinel solidsolution was used as the blackbody material, a test battery was formedin a manner similar to that of Example 1-1. In addition, when theemissivity of the blackbody material layer using a chromite spinel solidsolution was measured as in Example 1-1, the emissivity was 0.81.

Example 1-5

Except that when the laminate film was formed, aniline black was used asthe blackbody material, a test battery was formed in a manner similar tothat of Example 1-1. In addition, when the emissivity of the blackbodymaterial layer using aniline black was measured as in Example 1-1, theemissivity was 0.83.

Comparative Example 1-1

Except that a laminate film was formed in which no blackbody materiallayer was provided as in the above basic structure, a test battery wasformed in a manner similar to that of Example 1-1. In addition, since noblackbody material layer was provided in Comparative Example 1-1, whenthe emissivity of the aluminum metal layer was measured as in Example1-1, the emissivity was 0.12.

Comparative Example 1-2

Except that when the laminate film was formed, carbon black was used asthe blackbody material, and the content of the carbon black in theblackbody material layer was set to 45 percent by weight, a test batterywas formed in a manner similar to that of Example 1-1. In addition, whenthe emissivity of the blackbody material layer using carbon black ofComparative Example 1-2 was measured as in Example 1-1, the emissivitywas 0.53.

Evaluation of Battery

(a) High-Temperature Storage Test

The test batteries of the above examples and comparative examples wereeach charged to a voltage of 4.35 V and were then held in an oven at anenvironmental temperature of 130° C. Subsequently, after the testbatteries were each held for 30 minutes or 60 minutes in an environmentof a temperature of 130° C., the surface temperature of each testbattery was measured. The surface temperature of each test battery wasmeasured by pressing a thermocouple to the surface thereof.

In the following Table 1, the results of the above evaluation are shown.

TABLE 1 Blackbody material layer Content of Particle diameter blackbodyTemperature Temperature Structure of Blackbody of blackbody materialThickness after 30 after 60 laminate film material material (μm) (wt %)(μm) Emissivity minutes (° C.) minutes (° C.) Example 1-1 (1) Carbonblack 0.5 70 2.0 0.82 102 131 Example 1-2 (1) Graphite 0.5 70 2.0 0.85103 130 Example 1-3 (1) Graphite 0.5 70 2.0 0.79 102 132 Example 1-4 (1)Spinel solid 0.5 70 2.0 0.81 104 132 solution Example 1-5 (1) Anilineblack 0.5 70 2.0 0.83 105 131 Comparative Basic — — — — 0.12 115 144Example 1-1 structure — Comparative (1) Carbon black 0.5 45 2.0 0.53 111139 Example 1-2

As shown in Table 1, it was found that when the layer containing theblackbody material was provided in the laminate film, the heatdissipation characteristics were improved, and the surface temperatureof the battery after the high-temperature storage was not likely toincrease. In addition, it was also found that when the emissivity was0.6 or more as in Examples 1-1 to 1-5, a particularly significant effectcould be obtained as compared to Comparative Example 1-2.

Example 2

In Example 2, a battery pack was formed by changing the structure of thelaminate film, and the battery surface temperature in high-temperaturestorage was measured.

Example 2-1

A test battery was formed in a manner similar to that of Example 1-1.

Example 2-2

As shown in the above (2), a laminate film composed of an outer layerfilm/adhesive layer/blackbody material layer/metal foil/adhesivelayer/inner layer film was formed. In this case, the blackbody materiallayer was formed on the metal foil at an outer layer film side. Theblackbody material layer was formed by applying a blackbody solutionwhich contained 30 percent by weight of an acrylic resin and 70 percentby weight of carbon black to one surface of the metal foil to have athickness of 2.0 μm, the carbon black functioning as the blackbodymaterial and having an average particle diameter D50 of 0.5 μm. Exceptthat described above, a test battery was formed in a manner similar tothat of Example 1-1.

Example 2-3

As shown in the above (3), a laminate film composed of an outer layerfilm in which the blackbody material was dispersed/adhesive layer/metalfoil/adhesive layer/inner layer film was formed. In this case, as theouter layer film in which the blackbody material was dispersed, apoly(ethylene terephthalate) (PET) film which contained 70 percent byweight of the blackbody material and which had a thickness of 30 μm wasused. Except that described above, a test battery was formed in a mannersimilar to that of Example 1-1.

Example 2-4

As shown in the above (4), a laminate film composed of an outer layerfilm/adhesive layer in which the blackbody material was dispersed/metalfoil/adhesive layer/inner layer film was formed. In this case, as theadhesive layer in which the blackbody material was dispersed, anadhesive layer which contained 70 percent by weight of the blackbodymaterial and which had a thickness of 5 μm was used. Except thatdescribed above, a test battery was formed in a manner similar to thatof Example 1-1.

Example 2-5

As shown in the above (5), a laminate film composed of an outer layerfilm/blackbody material layer/outer layer film/adhesive layer/metalfoil/adhesive layer/inner layer film was formed. In this case, theblackbody material layer was formed on one surface of the outer layerfilm, and a poly(ethylene terephthalate) (PET) layer having a thicknessof 30 μm was formed on the surface of the blackbody material layerprovided on the outer layer film. Except that described above, a testbattery was formed in a manner similar to that of Example 1-1.

Example 2-6

As shown in the above (6), a laminate film composed of an outer layerfilm/adhesive layer/metal foil/adhesive layer/blackbody materiallayer/inner layer film was formed. In this case, the blackbody materiallayer was formed on the inner layer film at a metal foil side. Exceptthat described above, a test battery was formed in a manner similar tothat of Example 1-1.

Example 2-7

As shown in the above (7), a laminate film composed of an outer layerfilm/adhesive layer/metal foil/blackbody material layer/adhesivelayer/inner layer film was formed. In this case, the blackbody materiallayer was formed on the metal foil at an inner layer film side. Exceptthat described above, a test battery was formed in a manner similar tothat of Example 1-1.

Example 2-8

As shown in the above (8), a laminate film composed of an outer layerfilm/adhesive layer/metal foil/adhesive layer/inner layer film in whichthe blackbody material was dispersed was formed. In this case, as theinner layer film in which the blackbody material was dispersed, apolypropylene (PP) film which contained 70 percent by weight of theblackbody material and which had a thickness of 30 μm was used. Exceptthat described above, a test battery was formed in a manner similar tothat of Example 1-1.

Example 2-9

As shown in the above (9), a laminate film composed of an outer layerfilm/adhesive layer/metal foil/adhesive layer in which the blackbodymaterial was dispersed/inner layer film was formed. In this case, as theadhesive layer in which the blackbody material was dispersed, anadhesive layer which contained 70 percent by weight of the blackbodymaterial and which had a thickness of 5 μm was used. Except thatdescribed above, a test battery was formed in a manner similar to thatof Example 1-1.

Comparative Example 2-1

Except that a laminate film composed of an outer layer film/adhesivelayer/metal foil/adhesive layer/inner layer film, which contained noblackbody material layer as in the basic structure, was formed, a testbattery was formed in a manner similar to that of Example 1-1.

Evaluation of Battery

(a) High-Temperature Storage Test

The test batteries of the above examples and comparative example wereeach charged to a voltage of 4.35 V and were then held in an oven at anenvironmental temperature of 130° C. Subsequently, after the testbatteries were each held for 5 minutes, 10 minutes, 30 minutes or 60minutes in an environment of a temperature of 130° C., the surfacetemperature of each test battery was measured. The surface temperatureof each test battery was measured by pressing a thermocouple to thesurface thereof.

In the following Table 2, the results of the above evaluation are shown.

TABLE 2 Blackbody material layer Particle diameter Structure ofBlackbody Content of Temperature Temperature Temperature Temperature ofblackbody material- blackbody after after after after laminate Blackbodymaterial containing material Thickness 5 min. 10 min 30 min. 60 min.film material (μm) layer (wt %) (μm) (° C.) (° C.) (° C.) (° C.) Example(1) Carbon black 0.5 Blackbody 70 2.0 26 42 102 131 2-1 material layerExample (2) Carbon black 0.5 Blackbody 70 2.0 27 42 98 128 2-2 materiallayer Example (3) Carbon black 0.5 Outer layer 70 30 35 54 105 137 2-3film Example (4) Carbon black 0.5 Adhesive 70 5.0 31 48 98 129 2-4 layerExample (5) Carbon black 0.5 Blackbody 70 2.0 36 54 108 139 2-5 materiallayer Example (6) Carbon black 0.5 Blackbody 2-6 material 70 — 39 58 112142 layer Example (7) Carbon black 0.5 Blackbody 70 2.0 39 58 113 1432-7 material layer Example (8) Carbon black 0.5 Inner layer 70 30 41 61114 143 2-8 film Example (9) Carbon black 0.5 Adhesive 70 5.0 42 59 113144 2-9 layer Comparative Basic — — — — — 42 61 115 144 Examplestructure 2-1

As shown in Table 2, it was found that when the layer containing theblackbody material was provided in the laminate film, the heatdissipation characteristics were improved, and the surface temperatureof the battery after the high-temperature storage was not likely toincrease. In particular, it was also found that when the layercontaining the blackbody material was provided at the outside of thebattery with respect to the metal foil of the laminate film, the heatdissipation effect was further improved. The reason for this is believedthat when the layer containing the blackbody material is provided at theoutside of the metal foil, the time to propagate released heat to theouter surface can be decreased.

In addition, the blackbody material layer is preferably provided ascompared to the case in which the blackbody material is contained in theouter layer film, the inner layer film, or the adhesive layer. Thereason for this is believed that when the blackbody material iscontained in the outer layer film, the inner layer film, or the adhesivelayer, it is not easy to maintain properties of the film containing theblackbody material, and the film properties are liable to be degraded.For example, when the blackbody material is contained in the adhesivelayer, the adhesion effect thereof may be degraded in some cases.

It was found that compared to the structures of (3) and (4) in which theblackbody material was contained in the outer layer film and theadhesive layer, respectively, according to the structures of (1) and (2)in which the blackbody material layer was provided, significantly highheat dissipation characteristics can be obtained, in particular, in aperiod of 10 minutes from the start of the high-temperature storage. Inaddition, in the structure of (5) in which the two outer layer filmswere provided with the blackbody material layer interposed therebetween,although the heat dissipation effect was degraded due to an increase inthickness of the outer layer film, the heat dissipation effect was highas compared to that of the structures of (6) to (9) in which the layercontaining the blackbody material was provided inside the metal foil.

In addition, even in the case in which the layer containing theblackbody material was provided inside the metal foil, a higher heatdissipation effect was obtained when a laminate film in which theblackbody material layer was provided was used.

Example 3

In Example 3, a battery pack was formed using a laminate film in whichthe particle diameter of the blackbody material was changed, and thebattery surface temperature in high-temperature storage was measured.

Example 3-1

A test battery was formed in a manner similar to that of Example 1-1except that the particle diameter D50 of carbon black functioning as theblackbody material was set to 0.1 μM.

Example 3-2

A test battery was formed in a manner similar to that of Example 1-1except that the particle diameter D50 of carbon black functioning as theblackbody material was set to 0.3 μM.

Example 3-3

A test battery was formed in a manner similar to that of Example 1-1except that the particle diameter D50 of carbon black functioning as theblackbody material was set to 0.5 μM.

Example 3-4

A test battery was formed in a manner similar to that of Example 1-1except that the particle diameter D50 of carbon black functioning as theblackbody material was set to 0.75 μM.

Example 3-5

A test battery was formed in a manner similar to that of Example 1-1except that the particle diameter D50 of carbon black functioning as theblackbody material was set to 1.0 μM.

Example 3-6

A test battery was formed in a manner similar to that of Example 1-1except that the particle diameter D50 of carbon black functioning as theblackbody material was set to 2.0 μM.

Example 3-7

A test battery was formed in a manner similar to that of Example 1-1except that the particle diameter D50 of carbon black functioning as theblackbody material was set to 3.0 μm.

Comparative Example 3-1

A test battery was formed in a manner similar to that of Example 1-1except that the blackbody material layer was not provided in thelaminate film as in the above basic structure.

Evaluation of Battery

(a) High-Temperature Storage Test

The test batteries of the above examples and comparative example wereeach charged to a voltage of 4.35 V and were then held in an oven at anenvironmental temperature of 130° C. Subsequently, after the testbatteries were each held for 30 minutes or 60 minutes in an environmentof a temperature of 130° C., the surface temperature of each testbattery was measured. The surface temperature of each test battery wasmeasured by pressing a thermocouple to the surface thereof.

In the following Table 3, the results of the above evaluation are shown.

TABLE 3 Blackbody material layer Particle diameter of TemperatureTemperature Structure of Blackbody blackbody material Thickness after 30min. after 60 min. laminate film material ( μm) ( μm) (° C.) (° C.)Example 3-1 (1) Carbon black 0.1 2.0 96 119 Example 3-2 (1) Carbon black0.3 2.0 98 124 Example 3-3 (1) Carbon black 0.5 2.0 102 131 Example 3-4(1) Carbon black 0.75 2.0 103 133 Example 3-5 (1) Carbon black 1.0 2.0105 134 Example 3-6 (1) Carbon black 2.0 2.0 111 139 Example 3-7 (1)Carbon black 3.0 2.0 112 141 Comparative Basic — — — 115 144 Example 3-1structure

As shown in Table 3, it was found that in Examples 3-1 to 3-7 in whichthe blackbody material layer was provided, the heat dissipation effectwas improved as the particle diameter of the blackbody material wasdecreased, and that the heat dissipation effect was not likely to obtainas the particle diameter was increased. In addition, when the particlediameter of the blackbody material was increased, the thickness of theblackbody material layer was necessarily increased to obtain thestability thereof, and as a result, the volume efficiency of the batterypack was degraded in some cases.

Example 4

In Example 4, the heat dissipation effect of the battery pack wasconfirmed by changing the thickness of the inner layer film of thelaminate film.

Example 4-1

As in the case of Example 1-1, a test battery was formed using an innerlayer film having a thickness of 30 μm.

Example 4-2

A test battery was formed in a manner similar to that of Example 1-1except that the thickness of the inner layer film was set to 40 μm.

Example 4-3

A test battery was formed in a manner similar to that of Example 1-1except that the thickness of the inner layer film was set to 50 μm.

Example 4-4

A test battery was formed in a manner similar to that of Example 1-1except that the thickness of the inner layer film was set to 60 μm.

Example 4-5

A test battery was formed in a manner similar to that of Example 1-1except that the thickness of the inner layer film was set to 75 μm.

Example 4-6

A test battery was formed in a manner similar to that of Example 1-1except that the thickness of the inner layer film was set to 100 μm.

Comparative Example 4-1

A test battery was formed in a manner similar to that of Example 1-1except that the blackbody material layer was not provided in thelaminate film as in the above basic structure.

Evaluation of Battery

(a) High-Temperature Storage Test

The test batteries of the above examples and comparative example wereeach charged to a voltage of 4.35 V and were then held in an oven at anenvironmental temperature of 130° C. Subsequently, after the testbatteries were each held for 30 minutes or 60 minutes in an environmentof a temperature of 130° C., the surface temperature of each testbattery was measured. The surface temperature of each test battery wasmeasured by pressing a thermocouple to the surface thereof.

In the following Table 4, the results of the above evaluation are shown.

TABLE 4 Blackbody material layer Particle Thickness Structure ofdiameter of of inner Temperature Temperature laminate BlackbodyBlackbody Thickness layer film after 30 min. after 60 min. film materialmaterial (μm) (μm) (μm) (° C.) (° C.) Example 4-1 (1) Carbon black 0.52.0 30 102 131 Example 4-2 (1) Carbon black 0.5 2.0 40 105 133 Example4-3 (1) Carbon black 0.5 2.0 50 108 137 Example 4-4 (1) Carbon black 0.52.0 60 111 140 Example 4-5 (1) Carbon black 0.5 2.0 75 113 140 Example4-6 (1) Carbon black 0.5 2.0 100 114 142 Comparative Basic — — — 30 115144 Example 4-1 structure

As shown in Table 4, compared to Comparative Example 4-1 in which thelaminate film was used which had an inner layer film having a thicknessequivalent to that of Example 4-1 and which contained no blackbodymaterial layer, in Example 4-1 in which the laminate film containing theblackbody material layer was used, a high heat dissipation effect wasobtained. In addition, it was found that when the blackbody materiallayer was provided, and the thickness of the inner layer film waschanged, a higher heat dissipation effect was obtained as the thicknessof the inner layer film was decreased. It was also found that when thethickness of the inner layer film was large, the rate of heat conductionfrom the battery element became low, and hence heat generated in thebattery element was not sufficiently dissipated.

Example 5

In Example 5, the surface color of the laminate film was changed with orwithout providing the blackbody material layer, and detection accuracyof pinholes was confirmed.

Example 5-1

As shown in the above (1), a laminate film was formed to have thestructure of an outer layer film/blackbody material layer/adhesivelayer/metal foil/adhesive layer/inner layer film.

Comparative Example 5-1

As shown in the above basic structure, a laminate film was formed tohave the structure of an outer layer film/adhesive layer/metalfoil/adhesive layer/inner layer film.

(b) Conformation of Detection Limit of Diameter of Pinholes

After pinholes were formed in the laminate films of the example and thecomparative example, light was radiated from an inner layer film side,and the presence of pinholes was confirmed from an outer layer film sideby visual inspection. The diameter of pinholes was gradually decreased,and by the method described above, the detection limit of the diameterof pinholes was confirmed from the outer layer film side by visualinspection.

In the following Table 5, the results of the above evaluation are shown.

TABLE 5 Blackbody material layer Particle diameter of Surface colorDetection limit of Structure of Blackbody blackbody material Thicknessof laminate diameter of pinholes laminate film material (μm) (μm) film(mm) Example 5-1 (1) Carbon black 0.5 2.0 Black 0.275 Comparative Basicstructure — — — Silver 0.450 Example 5-1

As shown in Table 5, in Example 5-1 in which the surface color was madeblack by the blackbody material layer, the detection limit of thediameter of pinholes was 0.275 mm, and hence a sufficiently smallpinhole was confirmed as compared to the Comparative Example 5-1 inwhich the surface color was made silver and the detection limit of thediameter of pinholes was 0.450 mm.

As described above, when the blackbody material layer was providedoutside the metal foil, the surface color of the battery pack was madeblack, and hence the detection accuracy of pinholes, cracks, and thelike could be improved.

The present invention has been described with reference to theembodiments and examples; however, the present invention is not limitedto the above embodiments and examples and may be variously modifiedwithout departing from the scope of the present invention. For example,the materials and numerical values of the battery element and thelaminate film have been merely described by way of example, anddifferent materials and numerical values may also be used.

In addition, as for the structure of the laminate film which includesthe layer containing the blackbody material, the structure other thanthose shown in the embodiments of the present invention may also beused.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope and without diminishing itsintended advantages. It is therefore intended that such changes andmodifications be covered by the appended claims.

The application is claimed as follows:
 1. A nonaqueous electrolytebattery comprising: a battery element; and a package member forpackaging the battery element, wherein the package member includes anouter layer film, a layer which contains a blackbody material and whichhas an emissivity of 0.6 or more, a metal layer, and an inner layerfilm, and the layer containing the blackbody material is providedbetween the outer layer film and the metal layer.
 2. The nonaqueouselectrolyte battery according to claim 1, wherein the layer containingthe blackbody material is a blackbody material layer containing theblackbody material and a resin.
 3. The nonaqueous electrolyte batteryaccording to claim 2, wherein the package member further includes anadhesive layer between the blackbody material layer and the metal layer.4. The nonaqueous electrolyte battery according to claim 1, wherein thelayer containing the blackbody material is an adhesive layer containingthe blackbody material and an adhesive.
 5. The nonaqueous electrolytebattery according to claim 4, wherein the adhesive contains a urethaneresin, an acrylic resin, or a styrene resin.
 6. The nonaqueouselectrolyte battery according to claim 1, wherein the blackbody materialcomprises at least one of a carbon material, a silicate material, and ametal oxide material.
 7. The nonaqueous electrolyte battery according toclaim 1, wherein the blackbody material has an average particle diameterof 1.0 μm or less, and the layer containing the blackbody material has athickness of 1 to 5 μm.
 8. The nonaqueous electrolyte battery accordingto claim 7, wherein the blackbody material has an average particlediameter of 0.5 μm or less.
 9. The nonaqueous electrolyte batteryaccording to claim 1, wherein the content of the blackbody material is60 to 80 percent by weight of the layer containing the blackbodymaterial.
 10. The nonaqueous electrolyte battery according to claim 1,wherein the inner layer film has a thickness of 10 to 50 μm.
 11. Thenonaqueous electrolyte battery according to claim 1, wherein the batteryelement is received in a battery element receiving portion formed in thepackage member, and a peripheral portion of the battery element issealed.
 12. The nonaqueous electrolyte battery according to claim 1,wherein an electrolyte contained in the battery element contains anelectrolytic solution and a retainer containing a polymer compound whichretains the electrolytic solution.
 13. The nonaqueous electrolytebattery according to claim 1, wherein the layer containing the blackbodymaterial has CMY values of C (cyan), M (magenta), and Y (yellow) thatare all 70 or more.
 14. The nonaqueous electrolyte battery according toclaim 1, wherein the layer containing the blackbody material furthercontains an additive.
 15. The nonaqueous electrolyte battery accordingto claim 1, wherein the metal layer has a thickness of 50 to 150 μm. 16.The nonaqueous electrolyte battery according to claim 1, wherein theouter layer film contains a nylon (Ny), a poly(ethylene terephthalate)(PET), a poly(ethylene naphthalate) (PEN), a poly(butyleneterephthalate) (PBT), or a poly(butylene naphthalate) (PBN).
 17. Anonaqueous electrolyte battery comprising: a battery element; and apackage member for packaging the battery element, wherein the packagemember includes a protective layer, a layer which contains a blackbodymaterial and which has an emissivity of 0.6 or more, a metal layer, anda heat fusion layer, and the layer containing the blackbody material isprovided between the protective layer and the metal layer.